Sheet members are conventionally known for administering active components through skin. Examples include a patch disclosed in Patent Literature 1 below and a microneedle sheet as shown in FIG. 1 of the present application. Instruments for assisting in affixing a seat member are also known. Patent Literature 1 discloses an auxiliary implement for patch application. This auxiliary implement includes a backing having a surface larger than a patch, wherein on one surface of the backing there are provided an adhesive surface portion which is coated with a pressure-sensitive adhesive and serves for temporarily and peelably holding the patch, and a non-adhesive surface portion.